Management Accounting has been focused on stand-alone or individual management accounting techniques. What we have ignored are management accounting embedded business systems that could contribute to realize the long–term profitability of the firms. In this paper, we will discuss the management accounting embedded business systems from various aspects along with description of the historical research development of management accounting.

Sato（1975）insisted on superiority of product cost information from job-order costing comparing to process costing. We will explain cost accumulation process of job-order costing enables timely providing of product cost numbers, and those cost information would be more reliable. Our explanations on two cost accounting systems should support advocations by Sato（1975）.

There are two types of costing: cost accounting system as defined in “Cost Accounting Standard” and costing not linked with financial accounting. Here, we focus on costing not linked with financial accounting, which is the calculation of the product cost per unit. Although costing not linked with financial accounting is very important in practice, its theoretical study has not been developed yet. In this paper, the significance and characteristics of costing not linked with financial accounting are clarified by comparing it with cost accounting system.

This paper proposes the following two hypotheses. (1) The essence of Sales & Operations Planning (S&OP), which is the process of strictly projecting profits and losses based on Production-Sales-Inventory plan (PSI), is to maximize profit maximization utilizing PSI as a constraint. (2) Additionally, relaxation of PSI constraints such a shortening processing and lead times can produce shadow price benefits. These two hypotheses provide unexplored perspectives towards optimizing overall supply chain cost management.

We think that there are several problems about practices of Standard Cost Management;（1）The costs of time researches conducted for the standard-time determination and its update are high, （2）The determined standard may not be reflected the actual situation at the manufacturing site, and（3）We can’t easy to identify the cause of the unfavorable variance. To solve these problems, we introduce a new approach of cost control with IoT sensors. The advantages of this approach are as follows:（1）It is possible easier to reflect the actual situation at the manufacturing site, （2）It becomes easier to distinguish between normal and abnormal variances, and（3）We will easier to identify the causes of variances.